Mobile devices, once used solely for telephone communications, are used for a wide range of tasks and include various apparatus.
Korean patent publication 2013/0022831 to Ryoo describes a method of measuring distance, height and length of an object using a mobile communication terminal.
Chinese patent publication 202940864 to Wu Hao describes incorporating a distance sensor into a mobile phone.
Chinese patent publication 10334213 to Liu Guohua describes measuring distance using two cameras with a known distance between them.
These devices either lack sufficient accuracy or require additional hardware not included in many existing mobile devices.